The present invention relates generally to dental implants and, more particularly, to a method and apparatus for spatially positioning and angulating implanted fixtures with respect to existing bone tissue.
Various treatments currently exist for patients suffering from partial and full edentulous situations. Modernly, a majority of these edentulous patients are fitted with conventional removable prostheses, such as bridges and dentures. Unfortunately, utilization of a conventional dental prosthesis is often contraindicative for those edentulous patients suffering from insufficient retention, excessive resorption, functional disturbances (i.e. nausea and gagging) and/or unsatisfactory phonetics and esthetics.
As an alternative to wearing conventional dentures, the patient may be a candidate for surgical implantation of tissue integrated (i.e. osseointegrated) fixtures anchored in existing jawbone tissue and upon which a natural-looking prosthesis is retained. When property positioned and angulated, osseointegration of dental implants into vital existing jawbone tissue can provide a predictable prognosis for restoration or reconstruction of the fully or partially edentulous patient.
In most dental implants, an oral surgeon surgically prepares the patient's jaw and a restorative dentist fabricates the prosthetic device. However, prior to surgical implantation, the implant surgeon and the restorative dentist perform a standard clinical examination to evaluate the patient's prognosis for successful tissue integration. This pre-surgical protocol requires great care and precision in the determination of adequate bone volume and quality for satisfactory implant (i.e. fixture) placement so as to increase the prognosis of prosthodontic satisfaction.
In general, protocol for dental implantation includes two surgical procedures for implanting the anchors and attaching the abutments thereto, and the fabrication of the diagnostic and permanent prosthesis by the restorative dentist. Following implantation of the substructural anchors or fixtures, primary (non-angulated) and/or secondary (angulated) abutments are threadably or cementably affixed to the osseointegrated fixtures during the second surgical procedure. Following recuperation, the restorative dentist or prosthodontist fabricates the rigid framework of the permanent prosthesis for attachment to the abutments. Typically, the permanent prosthesis includes teeth or teeth and soft tissue analogues mounted directly to the rigid frame work.
As is known, successful abutment connection and dental prosthesis fabrication are largely dependent on proper placement, spacing and angulation of the implanted fixtures for providing a relatively uniform and functional load distribution and proper occlusal alignment with the opposing teeth or prosthesis. Therefore, surgical templates or stents are generally used by the oval surgeon during fixture implantation surgery for determining the desired "ideal" fixture location with respect to vital bone tissue. Conventional surgical templates or stents are adapted for use (i.e. placement in the patient's mouth) following flap reflection of the soft gingival-mucosal tissue. Such devices generally include one or more small diameter cylindrical guide tubes which are provided to orient and guide each of the various drilling tools (i.e. burs, twist drills and taps) with respect to the underlying bone tissue. The long axis of the cylindrical guide tubes are "angulated" based on results of the diagnostic evaluation and are oriented to direct the drill tools passing therethrough along a predetermined "line-of-action" for drilling the implant bore in a region of adequate bone volume. Unfortunately, conventional templates and stents generally limit the surgeon's direction of flap reflection, impede access and visibility and, most importantly, inhibit the surgeon's ability to controllably variate angulation requirements in view of unanticipated bone trajectory variations.
During implant surgery, it is not uncommon for the surgeon to find the template or stent to be inappropriate after surgical reflection of the soft gum tissue has occurred. When this occurs, the surgeon can either suture the flap and fabricate a new template or continue the surgical procedure using clinical judgement for "free-hand" fixture placement in an effort to approximate fixture location, spacing and angulation with respect to the "ideal" presurgical site. Such free-hand fixture placement generally results in the use of secondary angulated abutments in an effort to eliminate or minimize excessively aberrant implant angulation. Moreover, errors in implanted fixture orientation can easily propagate into potentially unacceptable prosthesis esthetic and functional characteristics. As such, the restorative dentist is faced with the extremely difficult task of fabricating a permanent prosthesis which overcomes the aberrant implant angulation while maintaining the functional and esthetic characteristic of the diagnostic prosthesis previously approved by the patient.